Are you a "thin affiliate?"

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An explanation of what Google perceives as "thin affiliate" content and "sites with little or no added value"

[ame="http://www.youtube.com/watch?v=w3-obcXkyA4"]Thin content with little or no added value - YouTube[/ame]

This is one of several videos they released explaining manual penalties. They will now be giving notice of manual penalties in Webmaster Tools, so you may want to use it and verify your sites, if you aren't already.

Full article on all the penalty types overy at Search Engine Land - http://searchengineland.com/google-releases-six-videos-on-typical-manual-spam-actions-169226